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We report on a novel amplifier configuration concept for a 10 kW laser system using a zig-zag optical path based on a cryogenic Yb:YAG Total-Reflection Active-Mirror (TRAM) laser. The laser material is a compact composite ceramic, in which three Yb:YAG TRAMs are combined in series to increase the output power. Output powers of up to 214 W with a slope efficiency of 63% have been demonstrated for CW operation, even at a quite low pump intensity of less than 170 W/cm2. Further scaling could achieve output powers of more than 10 kW.

We have demonstrated a high-power laser oscillator with end-cooling using a sapphire-sandwiched Yb:YAG disk at near liquid nitrogen temperature. An output power of 75 W with a near-diffraction-limited beam was obtained from a 0.6-mm thick activemedium. The slope efficiency and themaximum optical-optical efficiency were 80 and 70%, respectively, with respect to absorbed pump power. [ABSTRACT FROM AUTHOR]

Ultra intense laser interaction with solids is crucially modified by the presence of the plasma layer created by the prepulse associated with the peak intensity pulse. Here interferometric measurements of the preplasma created by a 40 TW, 600 fs Nd-glass laser are reported. Density profile and its target dependence are measured and the predicted scale length dependence on target atomic number is confirmed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spherical solid tin targets were illuminated uniformly with twelve beams from the Gekko XII laser system to create spherical plasmas, and the extreme ultraviolet (EUV) emission spectra from the plasmas were measured. The highest conversion efficiency of 3% to 13.5 nm EUV light in 2% bandwidth was attained for an irradiance of around 5×1010 W/cm2. The experimental results were reproduced fairly well using a theoretical model taking the power balance in the plasma into consideration. [ABSTRACT FROM AUTHOR]

Properties of extreme ultraviolet (EUV) emission from laser-produced Sn and SnO2 plasmas were investigated. EUV emission images were taken with a monochromatic imager for 13.5 nm with 4% bandwidth. It was found that the EUV emitting plasma is not formed symmetrically with respect to the target surface normal but extends toward laser incident axis. This result is consistent with the angular distribution of EUV emission peaked toward the direction nearly perpendicular to the laser axis. The asymmetric plasma can be attributed to the interaction of a long laser pulse with expanding plasma along the path of laser incidence. [ABSTRACT FROM AUTHOR]